[Iron status and effect of early iron supplementation on sub-clinical iron deficiency in rural school-age children from mountainous areas of Beijing].

Objective: To understand iron nutritional status in school-age children, incidence of the sub-clinical iron deficiency (SID) and effect of iron supplementation on SID in the rural school-age children from mountainous areas of Beijing.
Methods: The dietary survey and food frequency questionnaire survey were conducted in 1,012 school children aged 7 - 13 at rural mountainous areas of Fangshan District, Beijing, and their blood samples were collected for analyzing biochemical indicators for iron nutrition. Two hundred and sixty-seven children with IDs (iron deficiency store) and IDE (iron deficiency erythropoiesis), based on screening criteria for iron-deficiency anemia, received an iron supplementation (NaFeEDTA) capsule (containing 60 mg iron element) weekly, and those with IDA (iron deficiency anemia) received NaFeEDTA capsule thrice weekly for nine weeks. Blood biochemical indicators for iron nutrition were determined repeatedly and compared with those before and after the intervention.
Results: The daily average intakes of energy, protein, iron and vitamin C in school children of all age groups reached the daily recommended criteria (> 85% of the RNIs), but the proportion of heme in dietary iron constitution was lower. The average blood biochemical indicators for iron nutrition were as follows: serum ferritin (SF) (50.83 +/- 33.09) micro g/L, free erythrocyte protoporphyrin (FEP) (489.44 +/- 219.61) micro g/L, hemoglobin (Hb) (130.57 +/- 10.82) g/L, and the ratio of FEP/Hb (3.83 +/- 1.96), respectively. Incidence of total iron deficiency in rural children was 26.5%, with proportions of iron deficiency (IDs), iron deficiency erythropoiesis (IDE), and iron deficiency anemia (IDA) of 15.5%, 7.1%, and 3.9% respectively. SID accounted for 85.4% of the total iron deficiency, which was 5.8 times as much as IDA. With iron supplementation for 9 weeks, the hematdogical index of iron increased significantly and returned to the normal level.
Conclusions: The incidence of subclinical iron deficiency in the rural school-age children was insidious and should be attached more importance, which was helpful to its early recognition and intervention. Iron supplementation is important for children with SID to prevent and decrease the occurrence of IDA.